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vf_geq.c
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1 /*
2  * Copyright (C) 2006 Michael Niedermayer <michaelni@gmx.at>
3  * Copyright (C) 2012 Clément Bœsch <ubitux@gmail.com>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; either version 2 of the License, or
10  * (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License along
18  * with FFmpeg; if not, write to the Free Software Foundation, Inc.,
19  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
20  */
21 
22 /**
23  * @file
24  * Generic equation change filter
25  * Originally written by Michael Niedermayer for the MPlayer project, and
26  * ported by Clément Bœsch for FFmpeg.
27  */
28 
29 #include "libavutil/avstring.h"
30 #include "libavutil/eval.h"
31 #include "libavutil/opt.h"
32 #include "libavutil/pixdesc.h"
33 #include "internal.h"
34 
35 typedef struct {
36  const AVClass *class;
37  AVExpr *e[4]; ///< expressions for each plane
38  char *expr_str[4]; ///< expression strings for each plane
39  int framenum; ///< frame counter
40  AVFilterBufferRef *picref; ///< current input buffer
41  int hsub, vsub; ///< chroma subsampling
42  int planes; ///< number of planes
43 } GEQContext;
44 
45 #define OFFSET(x) offsetof(GEQContext, x)
46 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
47 
48 static const AVOption geq_options[] = {
49  { "lum_expr", "set luminance expression", OFFSET(expr_str[0]), AV_OPT_TYPE_STRING, {.str=NULL}, CHAR_MIN, CHAR_MAX, FLAGS },
50  { "cb_expr", "set chroma blue expression", OFFSET(expr_str[1]), AV_OPT_TYPE_STRING, {.str=NULL}, CHAR_MIN, CHAR_MAX, FLAGS },
51  { "cr_expr", "set chroma red expression", OFFSET(expr_str[2]), AV_OPT_TYPE_STRING, {.str=NULL}, CHAR_MIN, CHAR_MAX, FLAGS },
52  { "alpha_expr", "set alpha expression", OFFSET(expr_str[3]), AV_OPT_TYPE_STRING, {.str=NULL}, CHAR_MIN, CHAR_MAX, FLAGS },
53  {NULL},
54 };
55 
57 
58 static inline double getpix(void *priv, double x, double y, int plane)
59 {
60  int xi, yi;
61  GEQContext *geq = priv;
62  AVFilterBufferRef *picref = geq->picref;
63  const uint8_t *src = picref->data[plane];
64  const int linesize = picref->linesize[plane];
65  const int w = picref->video->w >> ((plane == 1 || plane == 2) ? geq->hsub : 0);
66  const int h = picref->video->h >> ((plane == 1 || plane == 2) ? geq->vsub : 0);
67 
68  if (!src)
69  return 0;
70 
71  xi = x = av_clipf(x, 0, w - 2);
72  yi = y = av_clipf(y, 0, h - 2);
73 
74  x -= xi;
75  y -= yi;
76 
77  return (1-y)*((1-x)*src[xi + yi * linesize] + x*src[xi + 1 + yi * linesize])
78  + y *((1-x)*src[xi + (yi+1) * linesize] + x*src[xi + 1 + (yi+1) * linesize]);
79 }
80 
81 //TODO: cubic interpolate
82 //TODO: keep the last few frames
83 static double lum(void *priv, double x, double y) { return getpix(priv, x, y, 0); }
84 static double cb(void *priv, double x, double y) { return getpix(priv, x, y, 1); }
85 static double cr(void *priv, double x, double y) { return getpix(priv, x, y, 2); }
86 static double alpha(void *priv, double x, double y) { return getpix(priv, x, y, 3); }
87 
88 static const char *const var_names[] = { "X", "Y", "W", "H", "N", "SW", "SH", "T", NULL };
90 
91 static av_cold int geq_init(AVFilterContext *ctx, const char *args)
92 {
93  GEQContext *geq = ctx->priv;
94  int plane, ret = 0;
95  static const char *shorthand[] = { "lum_expr", "cb_expr", "cr_expr", "alpha_expr", NULL };
96 
97  geq->class = &geq_class;
99 
100  if ((ret = av_opt_set_from_string(geq, args, shorthand, "=", ":")) < 0)
101  return ret;
102 
103  if (!geq->expr_str[0]) {
104  av_log(ctx, AV_LOG_ERROR, "Luminance expression is mandatory\n");
105  ret = AVERROR(EINVAL);
106  goto end;
107  }
108 
109  if (!geq->expr_str[1] && !geq->expr_str[2]) {
110  /* No chroma at all: fallback on luma */
111  geq->expr_str[1] = av_strdup(geq->expr_str[0]);
112  geq->expr_str[2] = av_strdup(geq->expr_str[0]);
113  } else {
114  /* One chroma unspecified, fallback on the other */
115  if (!geq->expr_str[1]) geq->expr_str[1] = av_strdup(geq->expr_str[2]);
116  if (!geq->expr_str[2]) geq->expr_str[2] = av_strdup(geq->expr_str[1]);
117  }
118 
119  if (!geq->expr_str[3])
120  geq->expr_str[3] = av_strdup("255");
121 
122  if (!geq->expr_str[1] || !geq->expr_str[2] || !geq->expr_str[3]) {
123  ret = AVERROR(ENOMEM);
124  goto end;
125  }
126 
127  for (plane = 0; plane < 4; plane++) {
128  static double (*p[])(void *, double, double) = { lum, cb, cr, alpha };
129  static const char *const func2_names[] = { "lum", "cb", "cr", "alpha", "p", NULL };
130  double (*func2[])(void *, double, double) = { lum, cb, cr, alpha, p[plane], NULL };
131 
132  ret = av_expr_parse(&geq->e[plane], geq->expr_str[plane], var_names,
133  NULL, NULL, func2_names, func2, 0, ctx);
134  if (ret < 0)
135  break;
136  }
137 
138 end:
139  return ret;
140 }
141 
143 {
144  static const enum PixelFormat pix_fmts[] = {
150  };
152  return 0;
153 }
154 
155 static int geq_config_props(AVFilterLink *inlink)
156 {
157  GEQContext *geq = inlink->dst->priv;
158  const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
159 
160  geq->hsub = desc->log2_chroma_w;
161  geq->vsub = desc->log2_chroma_h;
162  geq->planes = desc->nb_components;
163  return 0;
164 }
165 
167 {
168  int plane;
169  GEQContext *geq = inlink->dst->priv;
170  AVFilterLink *outlink = inlink->dst->outputs[0];
172  double values[VAR_VARS_NB] = {
173  [VAR_N] = geq->framenum++,
174  [VAR_T] = in->pts == AV_NOPTS_VALUE ? NAN : in->pts * av_q2d(inlink->time_base),
175  };
176 
177  geq->picref = in;
178  out = ff_get_video_buffer(outlink, AV_PERM_WRITE, outlink->w, outlink->h);
179  if (!out) {
181  return AVERROR(ENOMEM);
182  }
184 
185  for (plane = 0; plane < geq->planes && out->data[plane]; plane++) {
186  int x, y;
187  uint8_t *dst = out->data[plane];
188  const int linesize = out->linesize[plane];
189  const int w = inlink->w >> ((plane == 1 || plane == 2) ? geq->hsub : 0);
190  const int h = inlink->h >> ((plane == 1 || plane == 2) ? geq->vsub : 0);
191 
192  values[VAR_W] = w;
193  values[VAR_H] = h;
194  values[VAR_SW] = w / (double)inlink->w;
195  values[VAR_SH] = h / (double)inlink->h;
196 
197  for (y = 0; y < h; y++) {
198  values[VAR_Y] = y;
199  for (x = 0; x < w; x++) {
200  values[VAR_X] = x;
201  dst[x] = av_expr_eval(geq->e[plane], values, geq);
202  }
203  dst += linesize;
204  }
205  }
206 
208  return ff_filter_frame(outlink, out);
209 }
210 
212 {
213  int i;
214  GEQContext *geq = ctx->priv;
215 
216  for (i = 0; i < FF_ARRAY_ELEMS(geq->e); i++)
217  av_expr_free(geq->e[i]);
218  av_opt_free(geq);
219 }
220 
221 static const AVFilterPad geq_inputs[] = {
222  {
223  .name = "default",
224  .type = AVMEDIA_TYPE_VIDEO,
225  .config_props = geq_config_props,
226  .filter_frame = geq_filter_frame,
227  .min_perms = AV_PERM_READ,
228  },
229  { NULL }
230 };
231 
232 static const AVFilterPad geq_outputs[] = {
233  {
234  .name = "default",
235  .type = AVMEDIA_TYPE_VIDEO,
236  },
237  { NULL }
238 };
239 
241  .name = "geq",
242  .description = NULL_IF_CONFIG_SMALL("Apply generic equation to each pixel."),
243  .priv_size = sizeof(GEQContext),
244  .init = geq_init,
245  .uninit = geq_uninit,
247  .inputs = geq_inputs,
248  .outputs = geq_outputs,
249  .priv_class = &geq_class,
250 };